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The Truth About Starch Blockers

From the WebMD Archives

When you’re trying to shed pounds and the scale isn’t moving in the right direction, it can be tempting to want to try something else, like a no-prescription weight loss supplement.

Some of those supplements are called "starch blockers" or "carbohydrate blockers." They may seem like a good option because they claim to keep starches, and the calories found in them, from being digested.

But it's not quite that simple. If you're thinking about trying them for weight loss, keep in mind that claims for these products are not based on reliable scientific evidence. However, if you're using them in conjunction with a good diet and exercise program, they may help you to lose weight.

 

What Are Starch Blockers?

Starches are complex carbohydrates that cannot be absorbed unless they are first broken down by the digestive enzyme amylase. Amylase inhibitors, also called starch blockers, prevent starches from being absorbed by the body.  When amylase is blocked, those carbs pass through the body undigested, so you don't absorb the calories.

Some starch blockers need a prescription. They are called acarbose (Precose), and miglitol (Glyset). These are used as treatments for blood sugar control in people with type 2 diabetes.

There are also starch blockers that are sold without a prescription as supplements.

What's the difference?

Prescription drugs have to prove to the FDA that they are safe and effective. Supplements don't. You also can't be sure of what's in a supplement.

Some supplements may have unlisted ingredients, maybe stimulants, that could be dangerous for people with diabetes, says Kathleen Dungan, MD, an endocrinologist at Ohio State University.

Prescription versions won’t have those extra ingredients, so they tend to be safer.

The FDA has sent warning letters to makers of no-prescription starch blockers in the past, saying their marketing claims are misleading.

If you're considering using any product marketed for weight loss, talk to your doctor or a dietitian first. Ask yourself if it sounds too good to be true, and be skeptical.

Continued

Do They Work?

When it comes to shedding pounds, the evidence is not clear. There’s little data to support the use of herbal supplements as carb blockers, Dungan says.

As for side effects, you could get gas, bloating, stomach cramping, and diarrhea, she says.

Eat More Fiber

There’s another option if you’re looking to manage blood sugar levels and lose some weight: Add fiber to your diet.

“If you want to supplement your diet, you should do it naturally,” Dungan says.

Start by replacing simple carbohydrates with complex carbohydrates, she says. Look for foods low on the glycemic index (GI), which tend to have fiber to help you feel fuller longer.

Low GI foods that are high in fiber include whole grains, leafy vegetables, most fruits, and legumes.

Men should get 30-38 grams of fiber daily, and women should aim for 25 grams. But most people get only about 16 grams a day.

Talk to your doctor about any supplements you’re considering, and also how much fiber you should get to help manage your diabetes.

WebMD Feature Reviewed by Brunilda Nazario, MD on May 16, 2014

Sources

SOURCES:

Kathleen Dungan, MD, assistant professor, division of endocrinology, diabetes and metabolism, Ohio State University.

NYU Langone Medical Center: “Phaseolus vulgaris.”

Onakpoya, I. British Journal of Nutrition, July 2011.

University of California, San Francisco: “Starch Blocker.”

Harvard School of Public Health: “Carbohydrates.”

Institute of Medicine: “Dietary Reference Intakes.”

American Diabetes Association: “Glycemic Index and Diabetes” and “The American Deficit: Too Little Fiber.”

University of Maryland Medical Center: “Diabetes Diet.”

Howarth, N. Nutrition Reviews, May 2001.

Te Morenga,, L. Nutrition Journal, April 2011.

Sacks, F. New England Journal of Medicine, Feb. 26, 2009.

Mickelsen, O. The American Journal of Clinical Nutrition, Jan. 1, 1979.

FDA: "List of Distributors Receiving Warning Letters for Weight Loss Products" and "Beware of Fraudulent Weight-Loss 'Dietary Supplements.'"

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